summaryrefslogtreecommitdiffstats
path: root/libavcodec/mpeg12.c
blob: ab6c19c6151590026dd625f90cd608f4d97b679d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
/*
 * MPEG-1/2 decoder
 * Copyright (c) 2000, 2001 Fabrice Bellard
 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * MPEG-1/2 decoder
 */

#define UNCHECKED_BITSTREAM_READER 1

#include "libavutil/attributes.h"
#include "libavutil/avassert.h"
#include "libavutil/timecode.h"

#include "internal.h"
#include "avcodec.h"
#include "mpegvideo.h"
#include "error_resilience.h"
#include "mpeg12.h"
#include "mpeg12data.h"
#include "mpegvideodata.h"
#include "bytestream.h"
#include "thread.h"

uint8_t ff_mpeg12_static_rl_table_store[2][2][2*MAX_RUN + MAX_LEVEL + 3];

static const uint8_t table_mb_ptype[7][2] = {
    { 3, 5 }, // 0x01 MB_INTRA
    { 1, 2 }, // 0x02 MB_PAT
    { 1, 3 }, // 0x08 MB_FOR
    { 1, 1 }, // 0x0A MB_FOR|MB_PAT
    { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
    { 1, 5 }, // 0x12 MB_QUANT|MB_PAT
    { 2, 5 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
};

static const uint8_t table_mb_btype[11][2] = {
    { 3, 5 }, // 0x01 MB_INTRA
    { 2, 3 }, // 0x04 MB_BACK
    { 3, 3 }, // 0x06 MB_BACK|MB_PAT
    { 2, 4 }, // 0x08 MB_FOR
    { 3, 4 }, // 0x0A MB_FOR|MB_PAT
    { 2, 2 }, // 0x0C MB_FOR|MB_BACK
    { 3, 2 }, // 0x0E MB_FOR|MB_BACK|MB_PAT
    { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
    { 2, 6 }, // 0x16 MB_QUANT|MB_BACK|MB_PAT
    { 3, 6 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
    { 2, 5 }, // 0x1E MB_QUANT|MB_FOR|MB_BACK|MB_PAT
};

av_cold void ff_init_2d_vlc_rl(RLTable *rl, unsigned static_size, int flags)
{
    int i;
    VLC_TYPE table[680][2] = {{0}};
    VLC vlc = { .table = table, .table_allocated = static_size };
    av_assert0(static_size <= FF_ARRAY_ELEMS(table));
    init_vlc(&vlc, TEX_VLC_BITS, rl->n + 2, &rl->table_vlc[0][1], 4, 2, &rl->table_vlc[0][0], 4, 2, INIT_VLC_USE_NEW_STATIC | flags);

    for (i = 0; i < vlc.table_size; i++) {
        int code = vlc.table[i][0];
        int len  = vlc.table[i][1];
        int level, run;

        if (len == 0) { // illegal code
            run   = 65;
            level = MAX_LEVEL;
        } else if (len<0) { //more bits needed
            run   = 0;
            level = code;
        } else {
            if (code == rl->n) { //esc
                run   = 65;
                level = 0;
            } else if (code == rl->n+1) { //eob
                run   = 0;
                level = 127;
            } else {
                run   = rl->table_run  [code] + 1;
                level = rl->table_level[code];
            }
        }
        rl->rl_vlc[0][i].len   = len;
        rl->rl_vlc[0][i].level = level;
        rl->rl_vlc[0][i].run   = run;
    }
}

av_cold void ff_mpeg12_common_init(MpegEncContext *s)
{

    s->y_dc_scale_table =
    s->c_dc_scale_table = ff_mpeg2_dc_scale_table[s->intra_dc_precision];

}

void ff_mpeg1_clean_buffers(MpegEncContext *s)
{
    s->last_dc[0] = 1 << (7 + s->intra_dc_precision);
    s->last_dc[1] = s->last_dc[0];
    s->last_dc[2] = s->last_dc[0];
    memset(s->last_mv, 0, sizeof(s->last_mv));
}


/******************************************/
/* decoding */

VLC ff_mv_vlc;

VLC ff_dc_lum_vlc;
VLC ff_dc_chroma_vlc;

VLC ff_mbincr_vlc;
VLC ff_mb_ptype_vlc;
VLC ff_mb_btype_vlc;
VLC ff_mb_pat_vlc;

av_cold void ff_mpeg12_init_vlcs(void)
{
    static int done = 0;

    if (!done) {
        done = 1;

        INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12,
                        ff_mpeg12_vlc_dc_lum_bits, 1, 1,
                        ff_mpeg12_vlc_dc_lum_code, 2, 2, 512);
        INIT_VLC_STATIC(&ff_dc_chroma_vlc,  DC_VLC_BITS, 12,
                        ff_mpeg12_vlc_dc_chroma_bits, 1, 1,
                        ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514);
        INIT_VLC_STATIC(&ff_mv_vlc, MV_VLC_BITS, 17,
                        &ff_mpeg12_mbMotionVectorTable[0][1], 2, 1,
                        &ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 518);
        INIT_VLC_STATIC(&ff_mbincr_vlc, MBINCR_VLC_BITS, 36,
                        &ff_mpeg12_mbAddrIncrTable[0][1], 2, 1,
                        &ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 538);
        INIT_VLC_STATIC(&ff_mb_pat_vlc, MB_PAT_VLC_BITS, 64,
                        &ff_mpeg12_mbPatTable[0][1], 2, 1,
                        &ff_mpeg12_mbPatTable[0][0], 2, 1, 512);

        INIT_VLC_STATIC(&ff_mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7,
                        &table_mb_ptype[0][1], 2, 1,
                        &table_mb_ptype[0][0], 2, 1, 64);
        INIT_VLC_STATIC(&ff_mb_btype_vlc, MB_BTYPE_VLC_BITS, 11,
                        &table_mb_btype[0][1], 2, 1,
                        &table_mb_btype[0][0], 2, 1, 64);
        ff_rl_init(&ff_rl_mpeg1, ff_mpeg12_static_rl_table_store[0]);
        ff_rl_init(&ff_rl_mpeg2, ff_mpeg12_static_rl_table_store[1]);

        INIT_2D_VLC_RL(ff_rl_mpeg1, 680, 0);
        INIT_2D_VLC_RL(ff_rl_mpeg2, 674, 0);
    }
}

/**
 * Find the end of the current frame in the bitstream.
 * @return the position of the first byte of the next frame, or -1
 */
int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)
{
    int i;
    uint32_t state = pc->state;

    /* EOF considered as end of frame */
    if (buf_size == 0)
        return 0;

/*
 0  frame start         -> 1/4
 1  first_SEQEXT        -> 0/2
 2  first field start   -> 3/0
 3  second_SEQEXT       -> 2/0
 4  searching end
*/

    for (i = 0; i < buf_size; i++) {
        av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4);
        if (pc->frame_start_found & 1) {
            if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80)
                pc->frame_start_found--;
            else if (state == EXT_START_CODE + 2) {
                if ((buf[i] & 3) == 3)
                    pc->frame_start_found = 0;
                else
                    pc->frame_start_found = (pc->frame_start_found + 1) & 3;
            }
            state++;
        } else {
            i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1;
            if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) {
                i++;
                pc->frame_start_found = 4;
            }
            if (state == SEQ_END_CODE) {
                pc->frame_start_found = 0;
                pc->state=-1;
                return i+1;
            }
            if (pc->frame_start_found == 2 && state == SEQ_START_CODE)
                pc->frame_start_found = 0;
            if (pc->frame_start_found  < 4 && state == EXT_START_CODE)
                pc->frame_start_found++;
            if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) {
                if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) {
                    pc->frame_start_found = 0;
                    pc->state             = -1;
                    return i - 3;
                }
            }
            if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {
                ff_fetch_timestamp(s, i - 3, 1, i > 3);
            }
        }
    }
    pc->state = state;
    return END_NOT_FOUND;
}

#define MAX_INDEX (64 - 1)

int ff_mpeg1_decode_block_intra(GetBitContext *gb,
                                const uint16_t *quant_matrix,
                                uint8_t *const scantable, int last_dc[3],
                                int16_t *block, int index, int qscale)
{
    int dc, diff, i = 0, component;
    RLTable *rl = &ff_rl_mpeg1;

    /* DC coefficient */
    component = index <= 3 ? 0 : index - 4 + 1;

    diff = decode_dc(gb, component);
    if (diff >= 0xffff)
        return AVERROR_INVALIDDATA;

    dc  = last_dc[component];
    dc += diff;
    last_dc[component] = dc;

    block[0] = dc * quant_matrix[0];

    {
        OPEN_READER(re, gb);
        UPDATE_CACHE(re, gb);
        if (((int32_t)GET_CACHE(re, gb)) <= (int32_t)0xBFFFFFFF)
            goto end;

        /* now quantify & encode AC coefficients */
        while (1) {
            int level, run, j;

            GET_RL_VLC(level, run, re, gb, rl->rl_vlc[0],
                       TEX_VLC_BITS, 2, 0);

            if (level != 0) {
                i += run;
                if (i > MAX_INDEX)
                    break;

                j = scantable[i];
                level = (level * qscale * quant_matrix[j]) >> 4;
                level = (level - 1) | 1;
                level = (level ^ SHOW_SBITS(re, gb, 1)) -
                        SHOW_SBITS(re, gb, 1);
                SKIP_BITS(re, gb, 1);
            } else {
                /* escape */
                run = SHOW_UBITS(re, gb, 6) + 1;
                LAST_SKIP_BITS(re, gb, 6);
                UPDATE_CACHE(re, gb);
                level = SHOW_SBITS(re, gb, 8);
                SKIP_BITS(re, gb, 8);

                if (level == -128) {
                    level = SHOW_UBITS(re, gb, 8) - 256;
                    SKIP_BITS(re, gb, 8);
                } else if (level == 0) {
                    level = SHOW_UBITS(re, gb, 8);
                    SKIP_BITS(re, gb, 8);
                }

                i += run;
                if (i > MAX_INDEX)
                    break;

                j = scantable[i];
                if (level < 0) {
                    level = -level;
                    level = (level * qscale * quant_matrix[j]) >> 4;
                    level = (level - 1) | 1;
                    level = -level;
                } else {
                    level = (level * qscale * quant_matrix[j]) >> 4;
                    level = (level - 1) | 1;
                }
            }

            block[j] = level;
            if (((int32_t)GET_CACHE(re, gb)) <= (int32_t)0xBFFFFFFF)
               break;

            UPDATE_CACHE(re, gb);
        }
end:
        LAST_SKIP_BITS(re, gb, 2);
        CLOSE_READER(re, gb);
    }

    if (i > MAX_INDEX)
        i = AVERROR_INVALIDDATA;

    return i;
}
OpenPOWER on IntegriCloud